Ayvalık is a city on Turkey’s western (Aegean) coast. It lies about 3-4 km west of north-south highway D550/E87.
Ayvalık has two exits to D550/E87, one from the northern section of the city, and the other from the south. There is at least 5 km between each other.
South towards Izmir
Perhaps non-surprisingly, southern exit is better to head south. On the coastal promenade, when you see the big “Migros” store (about 20 min away from city centre on foot), you have arrived in a junction with traffic lights. Turn left at the junction, keep walking for about 10 minutes. At this point, the road lies through pine woods which offer shade that is perfect to hitchhike under during a sunny day. The shoulder isn’t very wide there, but it’s no problem as the traffic is not that heavy. You’ll attract a ride within approximately 20 minutes. Accept offer rides to Altınova junction (about 15-20 km south of Ayvalık), as it’s directly on the main highway and there are traffic lights on that junction.
On the Alibey-Cunda Island (which is connected to the mainland by a causeway and then a bridge, 6 km away from downtown Ayvalık, entrance from north of the city, attracting a ride towards there is hard but not impossible), there are lots of oliveyards to choose from to pitch your tent. However, keep in mind that all of the oliveyards are private property and thus nominally forbidden to camp. But if you arrive late at night, get up and break the camp early (like 6-7AM), and follow leave-no-trace-camping rules (no trash!), then no one will even find out you were there.
Pine woods to the south of the city may also be a good spot to spend the night.